Refactor calendar datasource architecture

Centralizes date calculation logic into DateColumnDataSource
Improves separation of concerns across rendering components

Key changes:
- Introduces IColumnInfo interface for flexible column data
- Moves date calculation from multiple managers to dedicated datasource
- Removes duplicate date rendering logic
- Prepares architecture for future resource-based views

src/renderers/EventRendererManager.ts

@@ -91,12 +91,15 @@ export class EventRenderingService {
      * Handle GRID_RENDERED event - render events in the current grid
      */
     private handleGridRendered(event: CustomEvent): void {
-        const { container, dates } = event.detail;
+        const { container, columns } = event.detail;
 
-        if (!container || !dates || dates.length === 0) {
+        if (!container || !columns || columns.length === 0) {
             return;
         }
 
+        // Extract dates from columns
+        const dates = columns.map((col: any) => col.data as Date);
+
         // Calculate startDate and endDate from dates array
         const startDate = dates[0];
         const endDate = dates[dates.length - 1];